It appears that you've solved your issue but, I'll post this for reference. I have an UltraDot mounted on a Weaver base that's been working well for me for many years.
Another high quality, low cost option is the small, lightweight, Bushnell Trophy TRS-25. I have it mounted on a couple of pistols and really like it's smaller 3 M.O.A. dot. I've included a photo of one mounted on an old, Browning Challenger.
